Nanoscale phenomena and especially surface plasmon-based optical devices are playing important roles in historical and emerging applications of photography, instrumentation, imaging, and signal processing. Simulation of these devices is synergistic with invention, and commercial computer-aided design infrastructure will eventually follow to cope with design and manufacturing. Devices based on source-free solutions to Maxwell's equations, such as plasmons and guided waves, are emphasized. They include the Daguerrotype and plasmon scattering from topographical features. A more general survey of the applications of simulation to optical nanodevices is also included. For finite-difference time domain using up to 250 million nodes, the major computational challenges are associated with the nm-level detail of large distributed structures, the small real part of the refractive index, and the necessity to accurately compute phases. (c) 2005 American Vacuum Society.